(1) Field of the Invention
The present invention relates to a process for producing an ether compound by the so-called ether exchange reaction, in which a different ether compound from the desired ether compound is reacted with a hydroxy group containing compound in the presence of a heteropoly acid or an acidic salt thereof as the catalyst.
(2) Description of the Prior Art
Conventionally, ether compounds have been produced by the following processes;
(a) Intermolecular dehydration process between same or different hydroxy group containing compounds. PA1 (b) So-called Williamson reaction process in which a halogenated hydrocarbon is reacted with a hydroxy group containing compound. PA1 (c) Condensation reaction process of a hydroxy group containing compound with a sulfuric acid ester. PA1 (d) Addition reaction process of an olefin to a hydroxy group containing compound. PA1 (e) Addition reaction process of an alkylene oxide to a hydroxy group containing compound.
These conventional processes can be applied only to specific ether compounds and have been inevitably accompanied with lots of by-products of which the disposal may be troublesome.
Besides these conventional processes, simple processes for producing specific ether compounds such as mono- or polyalkeneneglycol diethers were recently disclosed. (U.S. Pat. Nos. 4,146,436, 4,385,190 and 4,391,994). In these processes, raw materials are lower alkyl ether and alkylene oxide, which naturally can not be accompanied by lots of by-products. But the target of both these direct processes and the conventional process (e) is towards the production of specific ether compounds such as ethers having more than one oxyalkylene group. Moreover, highly reactive alkylene oxide is employed as one of the raw materials and the product is inevitably an ether mixture consisting of one or more insertion or addition products of the alkylene oxide, and optionally, not only the isolation of each ether is desired, but some of them are not always required. In the aforementioned mixture, are mingled by-products scarcely separated out from the mixture.
Another simple process in which ethyleneglycol monoalkyl ether is reacted with dialkyl ether by an ether-exchange reaction to ethyleneglycol dialkyl ether in the presence of the defined cation-exchange resin as the catalyst has been disclosed recently. (U.S. Pat. No. 4,231,413). This ether-exchange process is indeed new, but can not be applied to various kinds of ether compounds and the product is defined. This product is accompanied with a large amount of by-products, such as 1,4-dioxane due to the cyclization reaction of the raw material, ethyleneglycol monoalkyl ether and others due to the decomposition of the catalyst. Moreover, the catalyst is rapidly degraded, its efficient recovery or re-use is impossible, and the selection of reactor materials resistant to the corrosion in this process is very difficult.